1-millimeter band

The 1 millimeter band is a portion of the EHF (microwave) radio spectrum internationally allocated to amateur radio and amateur satellite use. The amateur radio and amateur satellite band is between 241 GHz and 250 GHz. Amateurs operate on a primary basis between 248 GHz and 250 GHz and on a secondary basis in the rest of the band. Also, amateurs must protect the radio astronomy service from harmful interference between 241 GHz and 248 GHz, the ITU's allocations are the same in all three ITU Regions.[1]

Some administrations have authorized spectrum for amateur use in this region.

1 This is not mentioned in the ITU's Table of Frequency Allocations, but individual administrations may make allocations under Article 4.4 of the ITU Radio Regulations. See the appropriate Wiki page for further information.2 HF allocation created at the 1979 World Administrative Radio Conference. These are commonly called the "WARC bands".3 This includes a currently active footnote allocation mentioned in the ITU's Table of Frequency Allocations, these allocations may only apply to a group of countries.

1.
Extremely high frequency
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Extremely high frequency is the International Telecommunications Union designation for the band of radio frequencies in the electromagnetic spectrum from 30 to 300 gigahertz. It lies between the high frequency band, and the far infrared band which is also referred to as the terahertz gap. Radio waves in this band have wavelengths from ten to one millimetre, giving it the name millimetre band or millimetre wave, millimetre-length electromagnetic waves were first investigated in the 1890s by Indian scientist Jagadish Chandra Bose. Compared to lower bands, radio waves in this band have high atmospheric attenuation, therefore, they have a short range and can only be used for terrestrial communication over about a kilometer. Absorption by humidity in the atmosphere is significant except in desert environments, however the short propagation range allows smaller frequency reuse distances than lower frequencies. The short wavelength allows modest size antennas to have a beam width. Millimeter waves propagate solely by line-of-sight paths, they are not reflected by the ionosphere nor do they travel along the Earth as ground waves as lower frequency radio waves do, at typical power densities they are blocked by building walls and suffer significant attenuation passing through foliage. The high free space loss and atmospheric absorption limits useful propagation to a few kilometers, thus they are useful for densely packed communications networks such as personal area networks that improve spectrum utilization through frequency reuse. They show optical propagation characteristics and can be reflected and focused by small metal surfaces around 1 ft. diameter, at millimeter wavelengths, surfaces appear rougher so diffuse reflection increases. Multipath propagation, particularly reflection from indoor walls and surfaces, causes serious fading, doppler shift of frequency can be significant even at pedestrian speeds. In portable devices, shadowing due to the body is a problem. Since the waves penetrate clothing and their small wavelength allows them to reflect from small metal objects they are used in millimeter wave scanners for security scanning. This band is used in radio astronomy and remote sensing. Ground-based radio astronomy is limited to high altitude such as Kitt Peak. Satellite-based remote sensing near 60 GHz can determine temperature in the atmosphere by measuring radiation emitted from oxygen molecules that is a function of temperature and pressure. The ITU non-exclusive passive frequency allocation at 57-59 and it is used commonly in flat terrain. The 71-76, 81-86 and 92–95 GHz bands are used for point-to-point high-bandwidth communication links. These higher frequencies do not suffer from oxygen absorption, but require a license in the US from the Federal Communications Commission

2.
Microwave
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Microwaves are a form of electromagnetic radiation with wavelengths ranging from one meter to one millimeter, with frequencies between 300 MHz and 300 GHz. Different sources define different frequency ranges as microwaves, the broad definition includes both UHF and EHF bands. A more common definition in radio engineering is the range between 1 and 100 GHz, in all cases, microwaves include the entire SHF band at minimum. Frequencies in the range are often referred to by their IEEE radar band designations, S, C, X, Ku, K, or Ka band. The prefix micro- in microwave is not meant to suggest a wavelength in the micrometer range and it indicates that microwaves are small, compared to waves used in typical radio broadcasting, in that they have shorter wavelengths. The boundaries between far infrared, terahertz radiation, microwaves, and ultra-high-frequency radio waves are fairly arbitrary and are used variously between different fields of study. At the high end of the band they are absorbed by gases in the atmosphere, microwaves are extremely widely used in modern technology. Although at the low end of the band they can pass through building walls enough for useful reception, therefore on the surface of the Earth microwave communication links are limited by the visual horizon to about 30 -40 miles. Microwaves are absorbed by moisture in the atmosphere, and the attenuation increases with frequency, beginning at about 40 GHz, atmospheric gases also begin to absorb microwaves, so above this frequency microwave transmission is limited to a few kilometers. A spectral band structure causes absorption peaks at specific frequencies, in a microwave beam directed at an angle into the sky, a small amount of the power will be randomly scattered as the beam passes through the troposphere. A sensitive receiver beyond the horizon with a high gain antenna focused on that area of the troposphere can pick up the signal. This technique has been used at frequencies between 0.45 and 5 GHz in tropospheric scatter communication systems to communicate beyond the horizon and their short wavelength allows narrow beams of microwaves to be produced by conveniently small high gain antennas from a half meter to 5 meters in diameter. Therefore beams of microwaves are used for point-to-point communication links, an advantage of narrow beams is that they allow frequency reuse by nearby transmitters. Parabolic antennas are the most widely used directive antennas at microwave frequencies, flat microstrip antennas are being increasingly used in consumer devices. Where omnidirectional antennas are required, for example in wireless devices and Wifi routers for wireless LANs, small monopoles, dipole, or patch antennas are used. Due to the high cost and maintenance requirements of waveguide runs, the term microwave also has a more technical meaning in electromagnetics and circuit theory. As a consequence, practical microwave circuits tend to away from the discrete resistors, capacitors. Open-wire and coaxial transmission lines used at lower frequencies are replaced by waveguides and stripline, high-power microwave sources use specialized vacuum tubes to generate microwaves

3.
Amateur radio
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The amateur radio service is established by the International Telecommunication Union through the International Telecommunication Regulations. National governments regulate technical and operational characteristics of transmissions and issue individual stations licenses with a call sign. Prospective amateur operators are tested for their understanding of key concepts in electronics, according to an estimate made in 2011 by the American Radio Relay League, two million people throughout the world are regularly involved with amateur radio. About 830,000 amateur radio stations are located in IARU Region 2 followed by IARU Region 3 with about 750,000 stations, a significantly smaller number, about 400,000, are located in IARU Region 1. The origins of amateur radio can be traced to the late 19th century, the First Annual Official Wireless Blue Book of the Wireless Association of America, produced in 1909, contains a list of amateur radio stations. This radio callbook lists wireless telegraph stations in Canada and the United States, as with radio in general, amateur radio was associated with various amateur experimenters and hobbyists. Amateur radio enthusiasts have significantly contributed to science, engineering, industry, research by amateur operators has founded new industries, built economies, empowered nations, and saved lives in times of emergency. Ham radio can also be used in the classroom to teach English, map skills, geography, math, science, the term ham radio was first a pejorative that mocked amateur radio operators with a 19th-century term for being bad at something, like ham-fisted or ham actor. It had already used for bad wired telegraph operators. Subsequently, the community adopted it as a moniker, much like the Know-Nothing Party, or other groups. Other, more entertaining explanations have grown up throughout the years, the many facets of amateur radio attract practitioners with a wide range of interests. Many amateurs begin with a fascination of radio communication and then combine other personal interests to make pursuit of the hobby rewarding, some of the focal areas amateurs pursue include radio contesting, radio propagation study, public service communication, technical experimentation, and computer networking. Amateur radio operators use various modes of transmission to communicate, the two most common modes for voice transmissions are frequency modulation and single sideband. FM offers high quality audio signals, while SSB is better at long distance communication when bandwidth is restricted. Radiotelegraphy using Morse code, also known as CW from continuous wave, is the extension of landline telegraphy developed by Samuel Morse. Morse, using internationally agreed message encodings such as the Q code, a similar legacy mode popular with home constructors is amplitude modulation, pursued by many vintage amateur radio enthusiasts and aficionados of vacuum tube technology. Demonstrating a proficiency in Morse code was for years a requirement to obtain an amateur license to transmit on frequencies below 30 MHz. Following changes in regulations in 2003, countries are no longer required to demand proficiency

4.
Amateur satellite
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An amateur radio satellite is an artificial satellite built and used by amateur radio operators for use in the Amateur-satellite service. These satellites use amateur radio frequency allocations to facilitate communication between amateur radio stations, many amateur-satellites receive an OSCAR designation, which is an acronym for Orbiting Satellite Carrying Amateur Radio. The designation is assigned by AMSAT, an organization which promotes the development, because of the prevalence of this designation, amateur radio satellites are often referred to as OSCARs. These satellites can be used for free by licensed radio operators for voice. Currently, over 5 fully operational amateur-satellites in orbit act as repeaters, linear transponders or store, throughout the years, amateur-satellites have helped make breakthroughs in the science of satellite communications. A few advancements include the launch of the first satellite voice transponder, the first amateur satellite, simply named OSCAR1, was launched on December 12,1961, barely four years after the launch of worlds first satellite, Sputnik I. The beginning of project was very humble. The satellite had to be built in a specific shape and weight. OSCAR1 was the first satellite to be ejected as a secondary payload, the satellite carried no on-board propulsion and the orbit decayed quickly. Despite being in orbit for only 22 days, OSCAR1 was a success with over 570 amateur radio operators in 28 countries forwarding observations to Project OSCAR. Most of the components for OSCAR10 were off the shelf, solar cells were bought in batches of 10 or 20 from Radio Shack and tested for efficiency by group members. The most efficient cells were kept for the project, the rest were returned to RadioShack, once ready, OSCAR10 was mounted aboard a private plane and flown on a couple of occasions to evaluate its performance and reliability. Special QSL cards were issued to those who participated in the airplane based flights, once it was found to be operative and reliable, the satellite was shipped to Kennedy Space Center where it was mounted in the third stage of the launch vehicle. Other programs besides OSCAR have included Iskra circa 1982, JAS-1 in 1986, RS, the first amateur satellites contained telemetry beacons. Since 1965, most OSCARs carry a linear transponder for two-way communications in real time, some satellites have a bulletin board for store-and-forward digital communications, or a digipeater for direct packet radio connections. Amateur satellites have been launched into low Earth orbits and into highly elliptical orbits, currently amateur-satellites support many different types of operation including FM voice, SSB voice, as well as digital communications of AX.25 FSK and PSK-31. Uplink and downlink designations use sets of paired letters following the structure X/Y where X is the uplink band, occasionally, the downlink letter is rendered in lower case. While deprecated, these older mode designations are still used in casual conversation

5.
ITU Region
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The International Telecommunication Union, in its International Radio Regulations, divides the world into three ITU regions for the purposes of managing the global radio spectrum. Each region has its own set of frequency allocations, the reason for defining the regions. Region 1 comprises Europe, Africa, the former Soviet Union, Mongolia, the western boundary is defined by Line B. Region 2 covers the Americas including Greenland, and some of the eastern Pacific Islands, the eastern boundary is defined by Line B. Region 3 contains most of non-FSU Asia east of and including Iran, the definition of the European Broadcasting Area uses some of the definitions of Region 1

6.
Amateur radio frequency allocations
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Amateur radio frequency allocation is done by national telecommunications authorities. Globally, the International Telecommunication Union oversees how much radio spectrum is set aside for radio transmissions. Individual amateur stations are free to use any frequency within authorized frequency ranges, Radio amateurs use a variety of transmission modes, including Morse code, radioteletype, data, and voice. Specific frequency allocations vary from country to country and between ITU regions as specified in the current ITU HF frequency allocations for amateur radio, the list of frequency ranges is called a band allocation, which may be set by international agreements, and national regulations. The modes and types of allocations within each band is called a bandplan, it may be determined by regulation. National authorities regulate amateur usage of radio bands, some bands may not be available or may have restrictions on usage in certain countries or regions. International agreements assign amateur radio bands which differ by region,2200 meters –135. 7–137.8 kHz – Very long antenna. This band lies far below the commercial AM broadcast band,600 meters – 472–479 kHz – This band lies just below the commercial AM broadcast band and marine band. 160 meters –1. 8-2 MHz – Often taken up as a technical challenge, long distance propagation tends to occur only at night, and the band can be notoriously noisy particularly in the summer months. 160 meters is known as the top band. Allocations in this band vary widely from country to country and this band lies just above the commercial AM broadcast band. 80 meters –3. 5–4.0 MHz – Best at night, works best in winter due to atmospheric noise in summer. Only countries in the Americas and few others have access to all of this band, in the US and Canada the upper end of the sub-band from 3600–4000 kHz, permits use of single-sideband voice as well as amplitude modulation, voice, often referred to as 75 meters. In most countries, the allocation is channelized and may require special application, voice operation is generally in upper sideband mode and in the USA it is mandatory. The 2015 ITU World Radiocommunications Conference approved a Worldwide Frequency Allocation of 5351. 5–5366.5 kHz to the Amateur Service on a secondary basis, the allocation limits amateur stations to 15 Watts effective isotropic radiated power, however some locations will be permitted up to 25 W EIRP. It will not come into effect until January 1,2017, Amateur stations will not be able to use this allocation until their national administration implements it. 40 meters –7. 0–7.3 MHz – Considered the most reliable all-season DX band, popular for DX at night,40 meters is also reliable for medium distance contacts during the day. Much of this band was shared with broadcasters, and in most countries the bottom 100 kHz or 200 kHz are available to amateurs,30 meters –10. 1–10.15 MHz – a very narrow band, which is shared with non-amateur services

7.
Low frequency
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Low frequency or LF is the ITU designation for radio frequencies in the range of 30 kHz–300 kHz. As its wavelengths range from ten kilometres to one kilometre, respectively, LF radio waves exhibit low signal attenuation, making them suitable for long-distance communications. In Europe and areas of Northern Africa and Asia, part of the LF spectrum is used for AM broadcasting as the longwave band, in the western hemisphere, its main use is for aircraft beacon, navigation, information, and weather systems. A number of time signal broadcasts are also broadcast in this band, because of their long wavelength, low frequency radio waves can diffract over obstacles like mountain ranges and travel beyond the horizon, following the contour of the Earth. This mode of propagation, called ground wave, is the mode in the LF band. Ground waves must be polarized, so monopole antennas are used for transmitting. The attenuation of signal strength with distance by absorption in the ground is lower than at higher frequencies, low frequency ground waves can be received up to 2,000 kilometres from the transmitting antenna. Low frequency waves can also travel long distances by reflecting from the ionosphere, although this method. Reflection occurs at the ionospheric E layer or F layers, skywave signals can be detected at distances exceeding 300 kilometres from the transmitting antenna. In Europe and Japan, many low-cost consumer devices have since the late 1980s contained radio clocks with an LF receiver for these signals. Since these frequencies propagate by ground wave only, the precision of time signals is not affected by varying propagation paths between the transmitter, the ionosphere, and the receiver. In the United States, such devices became feasible for the market only after the output power of WWVB was increased in 1997 and 1999. Radio signals below 50 kHz are capable of penetrating ocean depths to approximately 200 metres, the longer the wavelength, the British, German, Indian, Russian, Swedish, United States and possibly other navies communicate with submarines on these frequencies. In addition, Royal Navy nuclear submarines carrying ballistic missiles are allegedly under standing orders to monitor the BBC Radio 4 transmission on 198 kHz in waters near the UK. In the US, the Ground Wave Emergency Network or GWEN operated between 150 and 175 kHz, until replaced by satellite systems in 1999. GWEN was a land based military radio communications system which could survive, the 2007 World Radiocommunication Conference made this band a worldwide amateur radio allocation. An international 2.1 kHz allocation, the 2200 meter band, is available to amateur operators in several countries in Europe, New Zealand, Canada. The world record distance for a contact is over 10,000 km from near Vladivostok to New Zealand

8.
Medium frequency
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Medium frequency is the ITU designation for radio frequencies in the range of 300 kHz to 3 MHz. Part of this band is the medium wave AM broadcast band, the MF band is also known as the hectometer band or hectometer wave as the wavelengths range from ten to one hectometer. Frequencies immediately below MF are denoted low frequency, while the first band of frequencies is known as high frequency. MF is mostly used for AM radio broadcasting, navigational beacons, maritime ship-to-shore communication. A major use of frequencies is AM broadcasting, AM radio stations are allocated frequencies in the medium wave broadcast band from 526.5 kHz to 1606. Although these are medium frequencies,120 meters is generally treated as one of the shortwave bands, there are a number of coast guard and other ship-to-shore frequencies in use between 1600 and 2850 kHz. These include, as examples, the French MRCC on 1696 kHz and 2677 kHz, Stornoway Coastguard on 1743 kHz,2182 kHz is the international calling and distress frequency for SSB maritime voice communication. It is analogous to Channel 16 on the marine VHF band,500 kHz was for many years the maritime distress and emergency frequency, and there are more NDBs between 510 and 530 kHz. Navtex, which is part of the current Global Maritime Distress Safety System occupies 518 kHz and 490 kHz for important digital text broadcasts. Lastly, there are aeronautical and other mobile SSB bands from 2850 kHz to 3500 kHz, an amateur radio band known as 160 meters or top-band is between 1800 and 2000 kHz. Amateur operators transmit CW morse code, digital signals and SSB voice signals on this band, in recent years, some limited amateur radio operation has also been allowed in the region of 500 kHz in the US, UK, Germany and Sweden. Propagation at MF wavelengths is via ground waves and reflection from the ionosphere, ground waves follow the contour of the Earth. MF broadcasting stations use ground waves to cover their listening areas, however at certain times the D layer can be electronically noisy and absorb MF radio waves, interfering with skywave propagation. When this happens, MF radio waves can easily be received hundreds or even thousands of miles away as the signal will be refracted by the remaining F layer and this can be very useful for long-distance communication, but can also interfere with local stations. Due to the number of available channels in the MW broadcast band. On nights of good skywave propagation, the signals of distant stations may reflect off the ionosphere and interfere with the signals of local stations on the same frequency. These channels are called clear channels, and the stations, called stations, are required to broadcast at higher powers of 10 to 50 kW. Transmitting antennas commonly used on this band include monopole mast radiators, top-loaded wire monopole antennas such as the inverted-L and T antennas, ground wave propagation, the most widely used type at these frequencies, requires vertically polarized antennas like monopoles

9.
630-meter band
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It was formally allocated to amateurs at the 2012 World Radiocommunication Conference. The new WRC-12 allocation did not take effect until 1 January 2013. However, several countries previously allocated the WRC-12 band to amateurs domestically, previously, several other countries have authorized temporary allocations or experimental operations on nearby frequencies. The band is in the Medium Frequency region, within the greater 415–526.5 kHz maritime band, with maritime traffic largely displaced from 500 kHz band, some countries had taken steps prior to 2012 to allocate frequencies at or near 500 kHz to amateur radio use. During the 2012 World Radiocommunication Conference of the International Telecommunication Union, the frequencies studied were between 415 kHz and 526.5 kHz. The result was that 472–479 kHz was identified as agreeable for all three ITU Regions, except for countries such as Russia, China and Arab states. WRC-12 re-allocated the original 500 kHz frequency back to exclusive maritime mobile use for new navigation systems, following that, individual regulatory authorities need to implement the change nationally in order to make the allocation available to radio amateurs under their jurisdiction. Recently amateurs have experimented with radio communication near 474.2 kHz. Germany allocated the frequencies to amateur radio based on the WRC-12 conference, the Principality of Monaco allocated 472–479 kHz to the amateur service on 18 May 2012. The Philippines allocated 472–479 kHz to amateur radio, with a date of 30 August 2012. In New Zealand, the band 472 kHz to 479 kHz was allocated to radio, on a secondary basis. Amateur transmissions are limited to 25 watts EIRP, in Australia amateurs now have an allocation from 472 to 479 kHz, known as the 630 metre band. The maximum EIRP is 5 Watts, in Belgium, on 14 August 2013, a new allocation of 472 to 479 kHz has been added to the existing allocation of 501 to 504 kHz for ham-radio operators holding a HAREC-class license. The maximum EIRP is 5 Watts, in France amateurs have access to 472–479 kHz, with 1 Watt EIRP. In Norway, including Svalbard, Jan Mayen, and the Bouvet Island, maximum output power is 100 watts, and maximum EIRP of 1 Watt. In Poland, amateurs have an allocation from 472 to 479 kHz since 18 February 2014, the maximum EIRP is 1 Watt. In Canada, amateurs have an allocation from 472 to 479 kHz beginning 1 April 2014. In the United States of America, the Federal Communications Commission has approved 472 to 479 MHz on a basis to the amateur service in a report

10.
High frequency
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High frequency is the ITU designation for the range of radio frequency electromagnetic waves between 3 and 30 MHz. It is also known as the band or decameter wave as its wavelengths range from one to ten decameters. Frequencies immediately below HF are denoted medium frequency, while the band of higher frequencies is known as the very high frequency band. The HF band is a part of the shortwave band of frequencies. The band is used by shortwave broadcasting stations, aviation communication, government time stations, weather stations, amateur radio and citizens band services. By this method HF radio waves can travel beyond the horizon, around the curve of the Earth and it depends on the angle of incidence of the waves, it is lowest when the waves are directed straight upwards, and is higher with less acute angles. This means that at longer distances, where the waves graze the ionosphere at a blunt angle. The lowest usable frequency depends on the absorption in the layer of the ionosphere. This absorption is stronger at low frequencies and is stronger with increased solar activity. When all factors are at their optimum, worldwide communication is possible on HF, at many other times it is possible to make contact across and between continents or oceans. At worst, when a band is dead, no communication beyond the limited groundwave paths is possible no matter what powers, on such an open band, interference originating over a wide area affects many potential users. These issues are significant to military, safety and amateur radio users of the HF bands, other standards development such as STANAG5066 provides for error free data communications through the use of ARQ protocols. Noise, especially man-made interference from devices, tends to have a great effect on the HF bands. In recent years, concerns have risen among certain users of the HF spectrum over broadband over power lines Internet access and this is due to the frequencies on which BPL operates and the tendency for the BPL signal to leak from power lines. Some BPL providers have installed notch filters to block out certain portions of the spectrum, other electronic devices including plasma televisions can also have a detrimental effect on the HF spectrum. In aviation, HF communication systems are required for all trans-oceanic flights and these systems incorporate frequencies down to 2 MHz to include the 2182 kHz international distress and calling channel. The upper section of HF shares many characteristics with the part of VHF. The parts of this section not allocated to radio are used for local communications

11.
60-meter band
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The ITUs enhanced band allocation limits most amateurs to 15 watts effective isotropic radiated power, with some countries allowing 25 W EIRP. The ITU allocation will come into effect January 1,2017, in a number of countries the allocation is channelized at present, whereas others have block or band allocations. Voice operation is generally in upper sideband mode to facilitate inter-communication by non-amateur service users if necessary, in the United States and its Dependencies, channelized USB is mandatory. Where channelization is used, the USB suppressed carrier frequency is normally 1.5 kHz below the channel frequency. For example,5403.5 kHz is the frequency for the channel centered on 5405 kHz. The center of the channel is based on the assumption that the bandwidth of SSB transmissions are 3 kHz, transmitters that are capable of wider SSB bandwidths should be adjusted for 3 kHz bandwidth or less so their emissions stay within the allocated channel. Amateur equipment made in Japan and surrounding countries often did not originally support the 60 Meter allocation, however it is usually possible to modify such equipment to work correctly on these frequencies within the terms of the individuals licensing conditions. More recently, commercial radio equipment manufactured in Asia has begun to include provision for 60m/5 MHz operation. The amateur radio service is unusual in the fact that it is regulated by international treaty, at the conclusion of the ITU2012 World Radiocommunication Conference on Friday 17 February 2012, Resolution 649 was ratified as being placed on the Agenda for the following WRC in 2015. The full official ITU text can be found at, http, at the CITEL Regional Conference held in Mérida City, Mexico in October 2014, the conference recognised an IAP for a Secondary Amateur Allocation from 5275 to 5450 kHz. This was proposed by Brazil, together with Argentina, Uruguay, El Salvador, Dominican Republic and Nicaragua, the ITU2015 World Radiocommunication Conference took place in Geneva, Switzerland from 2 until 27 November 2015, where Agenda Item 1. 5–5366.5 kHz. Most stations are limited to 15 Watts EIRP, with the exception of Mexico, the allocation will go into effect from January 1,2017. An interim bandplan was adopted by IARU Region 1 in April 2016, the same bandplan was adopted by IARU Region 2 in October 2016. The bandplan strongly recommends that the WRC-15 frequencies should only be used if other 5 MHz frequencies, WRC-15 frequencies, like all others, can only be used when they have been licensed for amateur use by a countrys regulator. Information about the Critical Frequency of the Ionosphere at any one time is important for setting up. A number of these transmit 24/7 and some personal beacons are activated as required, call signs being, in transmission order - GB3RAL +0 minutes, GB3WES +1 minute and GB3ORK +2 minutes from approximately southern, central and northern locations in the UK. As of June 2016, GB3RAL and GB3ORK are off-air leaving only GB3WES active, discussions are taking place during 2016 as to the future of the UK5 MHz beacon system owing to the fact that its 5 MHz beacon licences are due to expire in 2017. From Spring 2011, it has been in operation h24 and is sequenced to transmit 2 minutes after the UK beacons, transmitting a USB-announcement, the South African Amateur Radio League - SARL - announced its intention to have a 5 MHz Beacon operational

12.
10-meter band
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The 10-meter band is a portion of the shortwave radio spectrum internationally allocated to amateur radio and amateur satellite use on a primary basis. The band consists of frequencies stretching from 28.000 to 29.700 MHz, the 10-meter band was allocated on a worldwide basis by the International Radiotelegraph Conference in Washington, D. C. on October 4,1927. Its frequency allocation was then 28000-30000 kc, a 300 kHz segment, from 29.700 MHz to 30.000 MHz, was removed from the amateur radio allocation by the 1947 International Radio Conference of Atlantic City. This was a windfall for amateur enthusiasts, allowing access to fairly inexpensive radios which could easily be modified for use in the 10-meter band. American Novice- and Technician-class licensees were granted CW and SSB segments on the 10-meter band as of 0001 UTC March 21,1987, being a very wide band in HF terms, many different transmission modes can be found on 10 meters. Morse code and other modes are found toward the bottom portion of the band, SSB from 28.300 MHz up. Digital modes, such as PSK-31, are allowed in the upper portion of the band. Due to its spot in the spectrum,10 meters can occasionally be challenging to work. At peak times of the cycle when many sunspots appear on the Suns surface,10 meters can be alive with extremely long-distance signals. Generally speaking, the most effective and efficient propagation of 10-meter radio waves takes place during daylight hours. During periods of increased activity, band openings may begin well before sunrise. Long-distance opportunities via F2 seem to follow the sun across the globe, in North America, for instance, F2 might bring Europe and western Asia in the morning, the Americas during midday, and the Pacific and East Asia in late afternoon and early evening. Even in times of minimum, when F2 is rarely available,10 meters still has some long distance possibilities. Sporadic E propagation can bring in signals from a hundred to thousands of miles away. Sporadic E on 10 meters is mainly a seasonal event, with late spring, a shorter, less-intense period occurs during mid-winter, often between Christmas and the new year. Other, off-peak openings may be seen almost anytime, even during solar minimum, F2 openings often occur on transequatorial paths, for example between Europe and Southern Africa or between Pacific North America and the Eastern Pacific islands. In tropical latitudes 10 meters is open throughout the sunspot cycle, for example, a good path from West Africa to the Caribbean exists on 10 meters even at solar minimum. Although 10 meters has an amateur radio allocation, in some countries the use of portions of 10 meters is allocated by the government by license class

13.
Very high frequency
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Very high frequency is the ITU designation for the range of radio frequency electromagnetic waves from 30 MHz to 300 MHz, with corresponding wavelengths of ten to one meters. Frequencies immediately below VHF are denoted high frequency, and the higher frequencies are known as ultra high frequency. Air traffic control communications and air navigation systems work at distances of 100 kilometres or more to aircraft at cruising altitude, some older DVB-T receivers included channels E2 to E4 but newer ones only go down to channel E5. VHF propagation characteristics are suited for terrestrial communication, with a range generally somewhat farther than line-of-sight from the transmitter. VHF waves are restricted to the radio horizon less than 100 miles. VHF is less affected by noise and interference from electrical equipment than lower frequencies. Unlike high frequencies, the ionosphere does not usually reflect VHF waves, the distance to the radio horizon is slightly extended over the geometric line of sight to the horizon, as radio waves are weakly bent back toward the Earth by the atmosphere. These approximations are only valid for antennas at heights that are compared to the radius of the Earth. They may not necessarily be accurate in mountainous areas, since the landscape may not be transparent enough for radio waves, in engineered communications systems, more complex calculations are required to assess the probable coverage area of a proposed transmitter station. The accuracy of calculations for digital TV signals is being debated. Portable radios usually use whips or rubber ducky antennas, while base stations usually use larger fiberglass whips or collinear arrays of vertical dipoles, for directional antennas, the Yagi antenna is the most widely used as a high gain or beam antenna. For television reception, the Yagi is used, as well as the log periodic antenna due to its wider bandwidth, helical and turnstile antennas are used for satellite communication since they employ circular polarization. For even higher gain, multiple Yagis or helicals can be mounted together to make array antennas, vertical collinear arrays of dipoles can be used to make high gain omnidirectional antennas, in which more of the antennas power is radiated in horizontal directions. Television and FM broadcasting stations use arrays of specialized dipole antennas such as batwing antennas. Certain subparts of the VHF band have the same use around the world, some national uses are detailed below. 108–118 MHz, Air navigation beacons VOR and Instrument Landing System localiser, 118–137 MHz, Airband for air traffic control, AM,121.5 MHz is emergency frequency 144–146 MHz, Amateur radio. Other capital cities and regional areas used a combination of these, the initial commercial services in Hobart and Darwin were respectively allocated channels 6 and 8 rather than 7 or 9. By the early 1960s it became apparent that the 10 VHF channels were insufficient to support the growth of television services and this was rectified by the addition of three additional frequencies—channels 0, 5A and 11

14.
6-meter band
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The 6-meter band is a portion of the very high frequency radio spectrum allocated to amateur radio use. Although located in the portion of the VHF band, it nonetheless occasionally displays propagation mechanisms characteristic of the high frequency bands. This normally occurs close to maximum, when solar activity increases ionization levels in the upper atmosphere. During the last sunspot peak of 2005, worldwide 6-meter propagation occurred making 6-meter communications as good as or in some instances and locations, the prevalence of HF characteristics on this VHF band has inspired amateur operators to dub it the magic band. Multiple-hop sporadic E propagation allows intercontinental communications at distances of up to 10,000 kilometres, in the southern hemisphere, sporadic E propagation is most common from November through early February. On October 10,1924, the 5-meter band was first made available to amateurs in the United States by the Third National Radio Conference, on October 4,1927, the band was allocated on a worldwide basis by the International Radiotelegraph Conference in Washington, D. C. 56–60 MHz was allocated for amateur and experimental use, there was no change to this allocation at the 1932 International Radiotelegraph Conference in Madrid. At the 1938 International Radiocommunication Conference in Cairo, television broadcasting was given priority in a portion of the 5-, the conference maintained the 56–60 MHz allocation for other regions and allowed administrations in Europe latitude to allow amateurs to continue using 56–58.5 MHz. Starting in 1938, the FCC created 6 MHz wide television channel allocations working around the 5-meter amateur band with channel 2 occupying 50–56 MHz. In 1940, television channel 2 was reallocated to 60 MHz, when the US entered World War II, transmissions by amateur radio stations were suspended for the duration of the war. After the war, the 5-meter band was briefly reopened to amateurs from 56–60 MHz until March 1,1946. At that time the FCC moved television channel 2 down to 54–60 MHz, FCC Order 130-C went into effect at 3 am Eastern Standard Time on March 1,1946 and created the 6-meter band allocation for the amateur service as 50–54 MHz. Emission types A1, A2, A3 and A4 were allowed for the entire band, at the 1947 International Radio Conference in Atlantic City, New Jersey, the amateur service was allocated 50–54 MHz in ITU Region 2 and 3. Broadcasting was allocated from 41 to 68 MHz in ITU Region 1, amateurs in the United Kingdom remained in the 5-meter band for a period of time following World War II, but lost the band to UK analogue television channel 4. They gained a 4-meter band in 1956 and eventually gained the 6-meter band from 50–52 MHz, the Radio Regulations of the International Telecommunication Union allow amateur radio operations in the frequency range from 50.000 to 54.000 MHz in ITU Region 2 and 3. At ITU level, Region 1 is allocated to broadcasting, however, in practice a large number of ITU Region 1 countries allow amateur use of at least some of the 6-meter band. Over the years portions have been vacated by VHF television broadcasting channels for one reason or another. In November 2015 the ITU World Radio Conference agreed that for their conference in 2019

15.
4-meter band
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The 4-metre band is an amateur radio frequency band in the lower very high frequency spectrum. The 4-metre band has a character and because very few countries have an allocation there. Therefore, most amateurs active on the band are interested in construction or modification of private mobile radio equipment. As a result, there is a lot of camaraderie on the band and long ragchews are the norm, before World War II, British radio amateurs had been allocated a band at 56 MHz. After the war ended, they were allocated the 5-metre band instead and this only lasted until 1949, as by then the 5-metre band had been earmarked for BBC Television broadcasts. In 1956, after years of intense lobbying by the Radio Society of Great Britain. For several years the 4-metre band allocation was only 200 kHz wide—from 70.2 MHz to 70.4 MHz and it was later extended to 70.025 MHz to 70.7 MHz. The band limits were moved to todays allocation of 70.0 MHz to 70.5 MHz. Whilst not formally allocated at an ITU or Regional level, in Europe CEPT now recognises the increased access to 70 MHz by radio amateurs with footnote EU9 which has helped underpin further growth. In practice this ranges from 70 MHz to 70.5 MHz in the United Kingdom, a table with national and regional allocations is pusblished and regularly updated on the Four Metres Website. The 4-metre band shares many characteristics with the neighbouring 6-metre band, although this has lessened in recent years, it can still cause considerable interference to both local and long distance operation. First ever transequatorial propagation contact on 70 MHz took place on 28 March 2011 between Leonidas Fiskas, SV2DCD, in Greece and Willem Badenhorst, ZS6WAB, in South Africa, access to the 4-metre band has always been limited by access to suitable 4-metre transceivers. A limited number of transceivers were purposely built for amateurs on this band while converted Private Mobile Radio equipment is in use e. g. Phillips FM1000. In the Sporadic E seasons communication around Europe is possible with such equipment, qixiang Electronics, the makers of the AnyTone and MyDel transceivers, have exported the AnyTone 5189 PMR 4m Mobile, and the AnyTone 3308 Handheld transceivers from China to the UK and to Europe. Both Transceivers have been selling well in the UK and in Europe. Recently a Monoband Multimode 70 MHz SSB/CW transceiver is released by NOBLE RADIO, at of this moment their 70 MHz transceiver is worldwide the only one available. There are three modern software defined radios which support the 4 meter band and they are the FLEX-6500 and FLEX-6700 by Flex Radio Systems, and the ICOM IC-7300. In some parts of the UK the band is little utilised, while in others, notably Belfast, Bristol, South and Mid Wales, North London, there is considerable AM activity in the Dublin area

16.
2-meter band
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The license privileges of amateur radio operators include the use of frequencies within this band for telecommunication, usually conducted locally within a range of about 100 miles. The Radio Regulations of the International Telecommunication Union allow amateur radio operations in the range from 144 to 148 MHz. In the US, that role in communications is furthered by the fact that most amateur-radio operators have a 2-meter handheld transceiver. Much of 2-meter FM operation uses a radio repeater, a receiver and transmitter that instantly retransmits a received signal on a separate frequency. Repeaters are normally located in locations such as a tall building or a hill top overlooking expanses of territory. On VHF frequencies such as 2-meters, antenna height greatly influences how far one can talk, typical reliable repeater range is about 25 miles. Some repeaters in unusually high locations, such as skyscrapers or mountain tops, reliable range is very dependent on the height of the repeater antenna and also on the height and surroundings of the handheld or mobile unit attempting to access to the repeater. Line of sight would be the ultimate in reliability, the typical hand held two meter FM transceiver produces about 5 watts of transmit power. Stations in a car or home provide higher power,25 to 75 watts, however, even without repeaters available, the 2-meter band provides reliable crosstown communications throughout smaller towns, making it ideal for emergency communications. Antennas for repeater work are almost always vertically polarized since 2-meter antennas on cars are usually vertically polarized, matching polarization allows for maximum signal coupling which equates to stronger signals in both directions. Simple radios for FM repeater operation have become plentiful and inexpensive in recent years, while the 2-meter band is best known as a local band using the FM Mode, there are many opportunities for long distance communications using other modes. The typical 2 meter station using CW or SSB modes consists of an exciter driving a power amplifier generating about 200–500 watts of RF power and this power is usually fed to a multi-element horizontally polarized, directional beam antenna knowns as a Yagi. Stations that are located in high locations with views clear to the horizon have a big advantage over other stations at lower elevations. Such stations are able to communicate 100–300 miles consistently and it is not unusual to be heard at distances much further and these distances can be traversed on a daily basis without any noticeable help from known Signal Enhancements. However, when coupled with well known signal enhancements, astonishing distances can be bridged. To traverse these distances, directional Yagi antennas are almost essential and are generally horizontally polarized and these antennas provide huge signal gains over a dipole or simple vertical and make communication over several hundred miles reliable. Meteor scatter, sporadic E, and tropospheric ducting are the most common forms of VHF signal enhancement and are described further below. These Openings as they are known, are generally first spotted by amateurs operating SSB, completion of contacts using these weak signal modes involves the exchange of signal level reports and location by grid square which is known as the Maidenhead Locator System

17.
1.25-meter band
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In the United States and Canada, the band is available on a primary basis from 222 to 225 MHz, with the addition of 219 to 220 MHz on a limited, secondary basis. It is not available for use in ITU Region 1 or ITU Region 3, the license privileges of amateur radio operators include the use of frequencies within this band, which is primarily used for local communications. The 1. 25-meter band has a long and colorful history dating back to before World War II. Some experimental amateur use in the U. S. was known to occur on the 1¼-meter band as early as 1933, in 1938 the FCC gave U. S. amateurs privileges in two VHF bands,2.5 meters and 1.25 meters. Both bands were natural harmonics of the 5-meter band, amateur privileges in the 2. 5-meter band were later reallocated to 144–148 MHz, and the old frequencies were reassigned to aircraft communication during World War II. At this time, the 1. 25-meter band expanded to a 5 MHz bandwidth, amateur use of VHF and UHF allocations exploded in the late 1960s and early 1970s as repeaters started going on the air. Repeater use sparked a huge interest in the 2-meter and 70-centimeter bands, however, many amateurs attribute this to the abundance of commercial radio equipment designed for 136–174 MHz and 450–512 MHz that amateurs could easily modify for use on the 2-meter and 70-centimeter bands. There were no commercial frequency allocations near the 1. 25-meter band, by the 1980s, amateur use of 2-meter and 70-centimeter bands was at an all-time high while activity on 1.25 meters remained stagnant. In an attempt to use on the band, many amateurs called for holders of Novice-class licenses to be given voice privileges on the band. In 1987, the FCC modified the Novice license to allow voice privileges on portions of the 1. 25-meter and 23-centimeter bands, in response, some of the bigger amateur radio equipment manufacturers started producing equipment for 1.25 meters. However, it never sold well, and by the early 1990s, in 1973, the FCC considered Docket Number 19759, which was a proposal to establish a Class E Citizens band service at 224 MHz. The proposal was opposed by the ARRL and after the growth of 27 MHz Citizens Band usage. In the late 1980s, United Parcel Service began lobbying the FCC to reallocate part of the 1. 25-meter band to the Land Mobile Service, UPS had publicized plans to use the band to develop a narrow-bandwidth wireless voice and data network using a mode called ACSSB. The reallocation proceeding took so long, however, that UPS eventually pursued other means of meeting its communications needs, UPS entered into agreements with GTE, McCall, Southwestern Bell, and Pac-Tel to use cellular telephone frequencies to build a wireless data network. Until January 2006, Canadian amateur radio operators were allowed operate within the entire 220–225 MHz band, in addition, the band 219 to 220 MHz was allocated to the amateur service on a secondary basis. Both of these went into effect January 2006. Today, the 1. 25-meter band is used by amateurs who have an interest in the VHF spectrum. There are pockets of widespread use across the United States, mainly in New England and western states such as California, the number of repeaters on the 1. 25-meter band has grown over the years to approximately 1,500 nationwide as of 2004

18.
Ultra high frequency
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Ultra high frequency is the ITU designation for radio frequencies in the range between 300 MHz and 3 GHz, also known as the decimetre band as the wavelengths range from one meter to one decimetre. Radio waves with frequencies above the UHF band fall into the SHF or microwave frequency range, lower frequency signals fall into the VHF or lower bands. UHF radio waves propagate mainly by line of sight, they are blocked by hills, the IEEE defines the UHF radar band as frequencies between 300 MHz and 1 GHz. Two other IEEE radar bands overlap the ITU UHF band, the L band between 1 and 2 GHz and the S band between 2 and 4 GHz. Radio waves in the UHF band travel almost entirely by propagation and ground reflection, there is very little reflection from the ionosphere. They are blocked by hills and cannot travel far beyond the horizon, atmospheric moisture reduces, or attenuates, the strength of UHF signals over long distances, and the attenuation increases with frequency. UHF TV signals are generally more degraded by moisture than lower bands, occasionally when conditions are right, UHF radio waves can travel long distances by tropospheric ducting as the atmosphere warms and cools throughout the day. The length of an antenna is related to the length of the radio waves used, the UHF antenna is stubby and short, at UHF frequencies a quarter-wave monopole, the most common omnidirectional antenna is between 2.5 and 25 cm long for example. UHF is widely used in telephones, cell phones, walkie-talkies and other two-way radio systems from short range up to the visual horizon. Their transmissions do not travel far, allowing frequency reuse, public safety, business communications and personal radio services such as GMRS, PMR446, and UHF CB are often found on UHF frequencies as well as IEEE802.11 wireless LANs. The widely adapted GSM and UMTS cellular networks use UHF cellular frequencies, radio repeaters are used to retransmit UHF signals when a distance greater than the line of sight is required. Omnidirectional UHF antennas used on mobile devices are usually short whips, higher gain omnidirectional UHF antennas can be made of collinear arrays of dipoles and are used for mobile base stations and cellular base station antennas. The short wavelengths also allow high gain antennas to be conveniently small, high gain antennas for point-to-point communication links and UHF television reception are usually Yagi, log periodic, corner reflectors, or reflective array antennas. At the top end of the band slot antennas and parabolic dishes become practical, for television broadcasting specialized vertical radiators that are mostly modifications of the slot antenna or helical antenna are used, the slotted cylinder, zig-zag, and panel antennas. UHF television broadcasting fulfilled the demand for additional over-the-air television channels in urban areas, today, much of the bandwidth has been reallocated to land mobile, trunked radio and mobile telephone use. UHF channels are used for digital television. UHF spectrum is used worldwide for mobile radio systems for commercial, industrial, public safety. Many personal radio services use frequencies allocated in the UHF band, major telecommunications providers have deployed voice and data cellular networks in UHF/VHF range

19.
23-centimeter band
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The 23 centimeter,1200 MHz or 1.2 GHz band is a portion of the UHF radio spectrum internationally allocated to amateur radio and amateur satellite use on a secondary basis. The amateur radio band is between 1240 MHz and 1300 MHz, the amateur satellite band is between 1260 MHz and 1270 MHz, and its use by satellite operations is only for up-links on a non-interference basis to other radio users. The allocations are the same in all three ITU regions, in the United Kingdom the band is between 1240 MHz and 1325 MHz. Most modes of communication used in amateur radio can be found in the 23 cm band, some of the more common modes include voice, data, EME, as well as ATV. Frequencies in the 23 cm band are harmonized by International Telecommunication Union region, CW and SSB calling frequency is 1296.2 MHz. FM simplex calling frequency is 1297.5 MHz, CW and SSB calling frequency is 1296.1 MHz. FM simplex calling frequency is 1294.5 MHz, FM Simplex Calling Frequency is 1294.0 MHz In 2008 the IARU Region-1 Cavtat Conference designated 1240. 000-1240.750 MHz as an alternative centre for narrowband activity and beacons. This is a mitigation for sharing with existing aviation radars and Primary users, or for potential issues with the European Galileo system

20.
13-centimeter band
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The 13 centimeter,2.3 GHz or 2.4 GHz band is a portion of the UHF radio spectrum internationally allocated to amateur radio and amateur satellite use on a secondary basis. The amateur radio band is between 2300 MHz and 2450 MHz, the amateur satellite band is between 2400 MHz and 2450 MHz, and its use by satellite operations is on a non-interference basis to other radio users. The license privileges of amateur radio operators include the use of frequencies, the allocations are the same in all three ITU Regions. Above 2400 MHz amateur stations must accept harmful interference caused by industrial, scientific, the most common ISM devices that operate in the band are microwave ovens. 2,304.1 MHz Region 2 CW & SSB calling frequency 2,320.2 MHz Region 1 Narrow-band calling frequency 2. 400-2,2,450 MHz Operating frequency of ISM devices. In the United States, the 13 cm band comprises frequencies in two segments stretching from 2.300 to 2.310 GHz, and from 2.390 to 2.450 GHz. The segment,2.390 to 2.417 GHz, is domestically allocated amateur radio on a primary basis and it is authorized to all amateur radio licensees who hold a Technician or higher class license, or a Basic or higher license. The band is allocated on a basis with other services. As in the rest of the world, US stations in the service are not protected from interference caused by industrial, scientific. The bandplan published by the American Radio Relay League recommends frequencies based on intended activity in the band, amateur radio frequency allocations High-speed multimedia radio

21.
Super high frequency
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Super high frequency is the ITU designation for radio frequencies in the range between 3 GHz and 30 GHz. This band of frequencies is known as the centimetre band or centimetre wave as the wavelengths range from one to ten centimetres. These frequencies fall within the band, so radio waves with these frequencies are called microwaves. This frequency range is used for most radar transmitters, wireless LANs, satellite communication, microwave relay links. Wireless USB technology is anticipated to use approximately one-third of this spectrum, frequencies in the SHF range are often referred to by their IEEE radar band designations, S, C, X, Ku, K, or Ka band, or by similar NATO or EU designations. Microwaves propagate entirely by line of sight, groundwave and ionospheric reflection do not occur, although in some cases they can penetrate building walls enough for useful reception, unobstructed rights of way cleared to the first Fresnel zone are usually required. Wavelengths are small enough at microwave frequencies that the antenna can be larger than a wavelength. Therefore, they are used in point-to-point terrestrial communications links limited by the visual horizon, such high gain antennas allow frequency reuse by nearby transmitters. The size of SHF waves allows strong reflections from objects the size of automobiles, aircraft, and ships. Thus, the narrow beamwidths possible with high gain antennas and the low atmospheric attenuation as compared with higher frequencies make SHF the main frequencies used in radar. Attenuation and scattering by moisture in the increase with frequency. Small amounts of energy are randomly scattered by water vapor molecules in the troposphere. This is used in communications systems, operating at a few GHz. A powerful microwave beam is aimed just above the horizon, as it passes through the some of the microwaves are scattered back to Earth to a receiver beyond the horizon. Distances of 300 km can be achieved and these are mainly used for military communication. The wavelengths of SHF waves are small enough that they can be focused into narrow beams by high gain antennas from a meter to five meters in diameter. Directive antennas at SHF frequencies are mostly aperture antennas, such as antennas, dielectric lens, slot. Large parabolic antennas can produce very narrow beams of a few degrees or less, for omnidirectional applications like wireless devices and cellphones, small dipoles or monopoles are used

22.
9-centimeter band
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The 9-centimeter band is a portion of the SHF radio spectrum internationally allocated to amateur radio and amateur satellite use. The amateur radio band, in ITU regions 1 and 2, is between 3,300 MHz and 3,500 MHz, and it is only on a secondary basis. The amateur satellite band is between 3,400 MHz and 3,410 MHz, and it is available in ITU Regions 1 and 2. In Germany and Israel, the band 3,400 -3,475 MHz is also allocated to the service on a secondary basis. In CEPTs European Common Allocation Table, footnote EU17 allocates 3,400 MHz to 3,410 MHz to European amateurs on a secondary basis, amateur stations voluntarily avoid using these frequencies when in geographic proximity to a radio telescope. ITU footnote 5.149 encourages all radio communications in the band to take steps to avoid harmful interference to radio astronomy observations in those frequency ranges

23.
5-centimeter band
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The 5 centimeter or 5 GHz band is a portion of the SHF radio spectrum internationally allocated to amateur radio and amateur satellite use on a secondary basis. In ITU regions 1 and 3, the radio band is between 5,650 MHz and 5,850 MHz. In ITU region 2, the radio band is between 5,650 MHz and 5,925 MHz. Amateur stations must accept interference from ISM users operating in the band. The band is within the IEEE C Band spectrum, the 5 cm band in the United States overlaps part of the U-NII band and all of 5 GHz ISM band. Both overlapping bands are available for applications such as WiFi or Part 15 devices. 5 cm is one of the bands for high-speed multimedia radio, as most U-NII. 5,668.2 MHz Region 1 Calling Frequency 15,760.1 MHz Region 2 Calling Frequency 5,760.2 MHz Region 1 Calling Frequency 25,800 MHz ISM band center frequency Amateur radio frequency allocations

24.
Terahertz radiation
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Photon energy in THz regime is less than band-gap of nonmetallic materials and thus THz beam can traverse through such materials. The transmitted THz beam is used for material characterization, layer inspection, terahertz radiation falls in between infrared radiation and microwave radiation in the electromagnetic spectrum, and it shares some properties with each of these. Like infrared and microwave radiation, terahertz radiation travels in a line of sight and is non-ionizing, like microwave radiation, terahertz radiation can penetrate a wide variety of non-conducting materials. Terahertz radiation can pass through clothing, paper, cardboard, wood, masonry, plastic, the penetration depth is typically less than that of microwave radiation. Terahertz radiation has limited penetration through fog and clouds and cannot penetrate liquid water or metal, THz is not ionizing yet can penetrate some distance through body tissue, so it is of interest as a replacement for medical X-rays. Due to its wavelength, images made using THz are low resolution. However, at distances of ~10 meters the band may still allow many useful applications in imaging and construction of high bandwidth wireless networking systems, terahertz radiation is emitted as part of the black-body radiation from anything with temperatures greater than about 10 kelvin. The opacity of the Earths atmosphere to submillimeter radiation restricts these observatories to very high altitude sites, and electronic oscillators based on resonant tunneling diodes have been shown to operate up to 700 GHz. There have also been solid-state sources of millimeter and submillimeter waves for many years, AB Millimeter in Paris, for instance, produces a system that covers the entire range from 8 GHz to 1000 GHz with solid state sources and detectors. Nowadays, most time-domain work is done via ultrafast lasers, in mid-2007, scientists at the U. S. The group was led by Ulrich Welp of Argonnes Materials Science Division, the device uses high-temperature superconducting crystals, grown at the University of Tsukuba in Japan. This alternating current induces an electromagnetic field, even a small voltage can induce frequencies in the terahertz range, according to Welp. In 2008, engineers at Harvard University achieved room temperature emission of several hundred nanowatts of coherent terahertz radiation using a semiconductor source, THz radiation was generated by nonlinear mixing of two modes in a mid-infrared quantum cascade laser. Previous sources had required cryogenic cooling, which limited their use in everyday applications. In 2009, it was discovered that the act of unpeeling adhesive tape generates non-polarized terahertz radiation, with a peak at 2 THz. In 2011, Japanese electronic parts maker Rohm and a team at Osaka University produced a chip capable of transmitting 1.5 Gbit/s using terahertz radiation. Such an antenna would broadcast in the frequency range. Unlike X-rays, terahertz radiation is not ionizing radiation and its low photon energies in general do not damage tissues, some frequencies of terahertz radiation can penetrate several millimeters of tissue with low water content and reflect back

25.
International Telecommunication Union
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ITU, based in Geneva, Switzerland, is a member of the United Nations Development Group. ITU has been an intergovernmental public-private partnership organization since its inception, ITU was formed in 1865, in Paris, at the International Telegraph Convention, this makes it one of the oldest intergovernmental organizations in the world. ITU became a United Nations specialized agency in 1947, the ITU comprises three sectors, each managing a different aspect of the matters handled by the Union, as well as ITU Telecom. The sectors were created during the restructuring of ITU at its 1992 Plenipotentiary Conference, radiocommunication Established in 1927 as the International Radio Consultative Committee or CCIR, this sector manages the international radio-frequency spectrum and satellite orbit resources. In 1992, the CCIR became the ITU-R, Standardization Standardization was the original purpose of ITU since its inception. Established in 1956 as the International Telephone and Telegraph Consultative Committee or CCITT, in 1993, the CCITT became the ITU-T. Development Established in 1992, this sector helps spread equitable, sustainable and affordable access to information and communication technologies, ITU Telecom ITU Telecom organizes major events for the worlds ICT community. A permanent General Secretariat, headed by the Secretary General, manages the work of the Union. The basic texts of the ITU are adopted by the ITU Plenipotentiary Conference, the ITU is headed by a Secretary-General, who is elected to a four-year term by the member states at the ITU Plenipotentiary Conference. On 23 October 2014 Houlin Zhao was elected 19th Secretary-General of the ITU at the Plenipotentiary Conference in Busan and his four-year mandate started on 1 January 2015, and he was formally inaugurated on 15 January 2015. There are 193 Member States of the ITU, which are all UN member states, the most recent member state to join the ITU is South Sudan, which became a member on 14 July 2011. The Republic of China was blocked from membership by the Peoples Republic of China, palestine was admitted as an observer in 2010. The Summit was held as two conferences in 2003 and 2005 in Geneva and Tunis, respectively, with the aim of bridging the digital divide, in December 2012, the ITU facilitated The World Conference on International Telecommunications 2012 in Dubai. WCIT-12 was a conference to address International Telecommunications Regulations, the international rules for telecommunications. The previous conference to update the Regulations was held in Melbourne in 1988, in August 2012, ITU called for a public consultation on a draft document ahead of the conference. Telecommunications ministers from 193 countries attended the conference in Dubai, the current regulatory structure was based on voice telecommunications, when the Internet was still in its infancy. In 1988, telecommunications operated under regulated monopolies in most countries, as the Internet has grown, organizations such as ICANN have come into existence to manage key resources such as Internet addresses and Domain Names. Some outside the United States believe that the United States exerts too much influence over the governance of the Internet, current proposals look to take into account the prevalence of data communications

Amateur radio (also called ham radio) describes the use of radio frequency spectrum for purposes of non-commercial …

An example of an amateur radio station with four transceivers, amplifiers, and a computer for logging and for digital modes. On the wall are examples of various amateur radio awards, certificates, and a reception report card (QSL card) from a foreign amateur station.

An amateur radio station in the United Kingdom. Multiple transceivers are employed for different bands and modes. Computers are used for control, datamodes, SDR and logging.

Extremely high frequency (EHF) is the International Telecommunication Union (ITU) designation for the band of radio …

Atmospheric attenuation in dB/km as a function of frequency over the EHF band. Peaks in absorption at specific frequencies are a problem, due to atmosphere constituents such as water vapour (H2O) and molecular oxygen (O2). The vertical scale is exponential.

Regions with allocations in the 60m amateur radio band. Blue regions have official allocations. Green regions issue experimental permits or licenses. Red regions have emergency-only allocations. Cyan regions have granted permission to only a few specific operations.

The 6-meter band is a portion of the very high frequency (VHF) radio spectrum allocated to amateur radio use. Although …

A Gonset Communicator II 6-meter AM transceiver. This vacuum tube radio with a magic eye tube tuning indicator, was affectionately known as a "Gooney Box" and was popular in the 1950s and 60s. A 2-meter version was also sold.

Low frequency (low freq) or LF is the ITU designation for radio frequencies (RF) in the range of 30 kilohertz (kHz)–300 …

Atmospheric radio noise increases with decreasing frequency. At the LF band and below, it is far above the thermal noise floor in receiver circuits. Therefore, inefficient antennas much smaller than the wavelength are adequate for reception

Super high frequency (SHF) is the ITU designation for radio frequencies (RF) in the range between 3 and 30 gigahertz …

A variety of parabolic antennas on a communications tower in Australia for point-to-point microwave communication links. Some have white plastic radomes over their apertures to protect against rain.

X-band (8 - 12 GHz) marine radar antenna on a ship. The rotating bar sweeps a vertical fan-shaped beam of microwaves around the water surface to the horizon, detecting nearby ships and other obstructions